1. Field of the Invention
The present invention relates to the use of novel cellulases with improved properties in detergents and aqueous laundry solutions. The invention further relates to detergents and detergent additives comprising the novel cellulase.
2. Discussion of the Related Art
Cellulases, also called cellulolytic enzymes, are enzymes which are capable of the hydrolysis of the .beta.-D-glucosidic linkages in celluloses. Cellulolytic enzymes have been divided traditionally into three classes: endoglucanases, exoglucanases or cellobiohydrolases and .beta.-glucosidases (Knowles, J. et al. (1987), TIBTECH 5, 255-261). Cellulolytic enzymes can be produced by a large number of bacteria, yeasts and fungi. Microorganisms that produce cellulases are described in for example GB-A-2094826.
Several applications have been developed for the use of cellulolytic enzymes:
degrading (wood) cellulose pulp into sugars for (bio)ethanol production; PA1 several textile treatments like `stone washing` and `biopolishing`; PA1 application in detergent compositions.
The use of cellulases in detergent compositions started with cellulases capable of reducing the harshness, i.e. softening of cotton containing fabrics, as described in for example GB-B-1358599.
It is further known that detergent compositions comprising cellulases are effective in removing dirt, i.e. cleaning. The efficiency of cellulolytic enzymes, cellulases, in terms of cleaning textile has been recognized for some time. GB-A-2075028, GB-A-2095275 and GB-A-2094826 disclose detergent compositions with cellulase for improved cleaning performance.
It is also known in the art that cellulases can act as a colour clarifying agent in laundry detergents. After repeated washing of soiled fabrics, cotton containing fabrics appear to be greyish, most probably due to disrupted fibres caused by mechanical action. The fibres are torn up resulting in disordered fibres which are broken. The use of cellulases as colour clarification agents for coloured fabrics has been described in EP-A-0220016. Actually cellulase mixtures from the fungal strain Humicola insolens (DSM 1800) are commonly used in detergents to result in antipilling and colour revival properties. The cellulolytic enzyme system produced by the wild type microorganism is available under the trade name of Celluzyme.RTM. by Novo-Nordisk. In addition a cloned (single) cellulase from the same origin under the trade name Carezyme.RTM. is also used in detergents.
The main disadvantage of the cellulases known in the art showing colour clarification is that these enzymes aggressively degrade the cellulose containing fabrics which results in damage by undesirable loss of tensile strength of the fabrics.
On the other hand cellulases known in the art showing good cleaning properties show hardly any colour clarification effects. The first commercial detergent with cellulases in the world contained a bacterial cellulase. This enzyme represents an above mentioned alkaline endoglucanase from a Bacillus species that does not attack cellulose fibres. The enzyme is described to give a cleaning effect during washing. No effects with respect to anti-pilling or colour revival have been described for this enzyme.
From the above it will become clear that it is still desirable to provide for improved cellulases in detergent applications. Using mixtures of cellulases, as suggested in international patent application WO-A-95/02675, is supposed to provide the above mentioned performance in laundry washing, but to our knowledge, it has not previously been possible to use single enzymes providing all these characteristics when applied in laundry washing.